A database stores a body of data in one or more records. An example of a database is a contact information database that stores records corresponding to entities (e.g., business organizations or individual persons) able to receive communications, where the records contain information usable to address communications to the entities. Another example of a database is a customer relationship management (CRM) system that stores records corresponding to entities, where the records contain information usable to manage business relationships with the entities. Management of a business relationship with an entity may involve addressing a communication to that entity.
A record may store data in one or more data fields that organize the data within the record. Within a record, a data field may contain stored data (e.g., a phone number, an e-mail address, a mailing address, or other contact information), or the data field may be empty (e.g., storing no data, or storing null data). For example, a database may be a text file in a computer file system that is stored on a disk drive. Within the text file, a record may be one line of text terminated by a new-line character, and individual data fields may be separated by comma characters. Between comma characters, data within a data field may be a sequence of characters (e.g., a word, a phrase, or a number). Two adjacent comma characters may indicate an empty data field. As another example, a database may be a table (e.g., a spreadsheet) where each row of the table is a record and each column of the table is a data field.
Different databases may store identical or similar data in one or more data fields that are similar in purpose, if not necessarily similar in name or format. For example, one database may contain a record having a data field labeled as “Work Phone,” while another database may contain a record having a data field labeled as “Business Phone.” The two records in the two databases may correspond to a single individual person, and both data fields may contain the same data, namely, a business-related phone number for the person. As another example, a record in one database may contain a data field for a “Work Area Code” and a separate data field for a “Work Phone Number,” while another record in another database may contain a single data field for a “Business Phone Number” that includes an area code.
Furthermore, the two data fields may contain different data. As an example, one data field in one database may contain a current phone number, and the other data field in the other database may contain an out-of-date phone number. As another example, one data field in one database may contain a current phone number, while the other data field in the other database may contain no phone number at all.